What the birds left behind -- a blessed mess

"Nature beckons you to be on her side. You couldn't ask for a better boss."
The quote is from Paul Hawken's commencement address, a speech that, days after I read it, is making me think deeply, and not entirely comfortably, on how I might "cast my lot with those who, age after age, perversely, with no extraordinary power, reconstitute the world."
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So if the birds weren't exactly bossing me around this past week, they definitely directed my garden work. Not only are coir-lined baskets environmentally-friendly, they're also a source of building material for birds like Mr. & Mrs. House Finch who have been deconstructing the hanging baskets without regard to tidiness as they tug out fibres, spill soil, discard the little bits, and fly away with full beaks to their nest site. (I suspect it's in a nearby tree with a view.) So everyday for the past couple of weeks I've been spending a good chunk of gardening time sweeping up the fibres, picking them out of the lettuce & other greens, and patching the liners with coffee filters. But I decided to leave the fibrous bits in the pots of polished rocks because...well, I like the natural, unkempt look & it reminds me of the birds who haven't been by for the past couple of days. I suspect their nest-building is complete. Now I just hope the crows don't get to the eggs or babies.
Next year I'm going to put a nesting box in my balcony garden. Does anyone have experience with this on a small balcony?